A foil image is known as an image having high-quality feel and high designability. The foil image is an image formed by adhesion of foil, such as metal foil, in a desired shape to a recording medium made of paper, fabric or the like. The foil image has been generally formed by pressing metal foil onto a recording medium by hot stamping or the like. In such a method, a plate (stamp) has been required to be formed along the shape of the foil image, and the foil image has been difficult to modify for each small lot and/or to form at a low cost. The foil image has been then demanded to be formed by digital printing or the like without use of any plate.
In recent years, decoration wallpaper and the like on which decoration is provided by digital printing have enjoyed popularity. Such decoration wallpaper has been produced by laminating a decoration sheet layer on lining paper, or directly providing decoration on lining paper (foil pressing or the like). A vinyl chloride sheet or the like is known as the decoration sheet layer, and a natural pulp substrate, a mixed substrate (non-woven fabric wallpaper) of natural pulp and a synthetic resin, or the like is known as the lining paper. Such a wallpaper material has also been demanded to have the foil image formed thereon, and the foil image has been demanded to be formed by digital printing in terms of production efficiency, cost, and the like.
In recent years, as the method for forming the foil image, a method has been proposed which includes transferring metal foil to a recording medium to which an adhesive has been applied in a desired shape, by heat-pressure bonding to form the foil image on the recording medium. For the adhesive, an aqueous adhesive having a microcapsule including a thermoplastic resin is used (see, for example, PTL 1).
An aqueous adhesive mainly includes water. Water has a lower volatilization rate than an organic solvent. Therefore, in the foil image forming method, the aqueous adhesive landed as droplets on the recording medium has a sufficiently high fluidity even on the recording medium. Accordingly, the aqueous adhesive landed may bleed on a recording medium having a high hydrophilicity. Furthermore, adjacent droplets of the aqueous adhesive landed may mutually coalesce on a recording medium having a low hydrophilicity, and thus be more roughly distributed in a patchy fashion. Such a phenomenon then occurs to easily impair fineness of the foil image.
Thus, the conventional foil image forming method using an aqueous adhesive has the problem of sometimes forming no predetermined foil image depending on hydrophilicity of a recording medium.
On the other hand, a method has also been proposed which includes forming an ink image by an actinic radiation-curable inkjet ink, and pressure bonding the ink image and transfer foil to allow the foil to be transferred in a pattern (for example, PTL 2).
Furthermore, a method has also been proposed which includes forming an ink image by an actinic radiation-curable inkjet ink, and temporarily curing the ink image and then pressure bonding it to transfer foil, to allow the foil to be transferred in a pattern (PTL 3).